Photodynamic therapy can be used for the treatment of a variety of oncological, cardiovascular, dermatological, and ophthalmic diseases. In cancer treatment, for example, photoactive materials can be preferentially localized in tumor tissues upon systemic administration and then can be irradiated to produce reactive species that can irreversibly damage cells. Under appropriate conditions, such a method can selectively destroy diseased tissues without damaging adjacent healthy tissues.
Many photoactive drugs and dyes are hydrophobic (due to at least some organic content), however, and this has required the development of various different delivery vehicles or carriers to enable the stable dispersion of such photoactive compounds into aqueous systems. Carriers have included oil-dispersions (micelles), liposomes, polymeric micelles, hydrophilic drug-polymer complexes, and so forth. Some such approaches have elicited hypersensitivity reactions, and others have suffered from relatively poor drug loading, self-aggregation of the drug, and/or accumulation of the drug in normal tissues.
Ceramic-based nanoparticles such as organically-modified silicates have also been doped with photoactive drugs or dyes for use as delivery vehicles. Such nanoparticles are generally quite stable, can effectively protect doped molecules from extreme pH and temperature conditions, can be easily functionalized with various different surface-modifying groups, and at least some are known for their compatibility with biological systems. Processes for the preparation of such doped ceramic-based nanoparticles have typically involved the use of organic solvent (which can hinder particle formation), however, and have suffered from other drawbacks such as the need for multiple process steps, multiple catalysts, formation of micellar compositions, and/or production of core-shell particle structures.